Since every leg is a little different and the tail section isn't perfectly symmetrical, I have to basically custom fit each leg to its section of the fuselage
So I'm just using a tiny piece of sandpaper and the tip of my finger. Making them out of softwood is coming in handy, as removing material is pretty easy.
I also found that rubbing the leg up and down while applying pressure makes slightly shiny spots that I can then sand.
It's a laborious but effective process
Use a piece of sandpaper (paper side against it, abrasive out) on the piece you’re trying to mate to, and it’ll sand in the same profile.
You should use a dowel instead of your finger since it doesn’t deform too much as well. Basically you should use a sanding backing block, in the same profile of what you’re trying to sand it too. Flat block for a flat area, dowels for round, stuff like that.
The sandpaper isn't flexible enough for that, it doesn't like to curve in two directions at once